Production of zinc sulfate.



sTATEs PATENT ()FFICE.

ANSON e. Burrs, or TROY, NEW YORK.

PRODUCTION OF ZINC SULFATE.

No Drawing.

To all whom, it may concern:

Be it known that I, ANSON G. Burrs, a citizen of the UnitedStates,residing "at Troy, in the county of Rensselaer and State of New York,have invented certain new and useful Improvements in the Production 'ofZinc Sulfate, of which the following is a full, clear, and exactdescription.

This invention relates to the lixiviation, with. dilute sulfuric orother acidfof oxidized or roasted zinc ore containingiron, and its chiefobject is'to dissolve out the zinc as a salt (by conversion of the ioxidto a salt) and prepares. solution free from iron in one and the sameoperation.

In treating roasted zinc ore with d lute acid, for example sulfuricacid, lIOII also dissolves (iron being almost always present in suchore) giving a solution of iron and zinc sulfates. The presence of ironinthe solution is objectionable when the solution for example)insufficient to convert all the zinc oxid into sulfate, on the theorythat zinc oxid will be completely converted into sulfate or other salt,according to the acid employed, before any of the ferric oxid (peroxidof iron) will be converted. However, this method has been found to beunsuccessful because it is necessary to leave some zinc undissolved,thereby causing a-loss of zinc;

and the method is unsuccessful too in not preventing the solution offerrous oxid (lower oxid of iron), which is almostalways, if not always,present ,in commercially roasted ore. It has beeruthe practice toafterward per-oxidize the ironin the solution by the addition ofoxidizing agents, and precipitate it out by adding zinc oxid, or roastedzinc ore, causing a voluminous slimy precipitate expensive to separateand resulting also in a loss of zinc in the precipi tate. and loss ofzinc in undissolved zinc oxid or incompletely leached zinc ore. The

rost of such iei'oxidation is somewl'iat high,

ailr u, due to the quantity of oxidizing chemicals necessz'irji.

Specification of Letters Patent.

Application filed December 9, 1912L .Serial No. 735,628.

Patented July 1, 1913.

l I am also aware that it has been proposed to extract zinc fromroastedv ores, by the treatment of said roasted ore with a solution offerric sulfate, containimg some free sulfuric acid, but this processis-open to the objection that the solution produced by thus treating theore, contains iron, partly from the iron of the original solution, andpartly as iron dissolved'from the roasted ore.

With my invention I accomplish the same object with a small portion 'ofthe cost and with much less delay and difficulty, by adding a smallquantity of peroxid-izing chemi cal stronger in its action than ferricsulfate solution, to the dilute sulfuric acid used for lixiviating. Achromate or chromic .acid (which are chemically equivalent in theprocess), or a permanganate, or permanganic acid, is suitable. A verysmall quantity is sufficient. I am not at present able to offer anychemical explanation of the action 'of the oxidizing agent in preventingthe solutlon of the lron 1n the ore, but can only usually possible todissolve all the zinc presentin roasted ore with diluted sulfuric acid,an extraction of 90%, for example, being considered about the best thatcan be done.

By means of this process, I can extract from low'grade ore as much as90% of the zinc, withoutdissolving any of the iron present. As beforestated, the process is not limited to'the production of. sulfate, butmay be used to produce other salts if desired. It is especiallyap'plicableio the production of sulfate, as the sulfate is the mostimportant for the electrolytic production of zinc from the solution, andthe iron-free solution is especially suitable for the purpose mentionedor for the crystallization of pure zinc sulfate.

What I claim is: p

1. In extracting zinc from material containing zinc in the form ofoxid,the treatment of said material with sulfuric acid in the presence of anoxidizing agent stronger in its oxidizing action than ferric sulfate.

2. In extracting zinc from material con tnining zinc in the form ofoxid, the treat ment of said material with sulfuric acid in the presenceof an oxidizing agent comprisinga compound of an element which acts acompound containing manganese as an' acid-forming element. Y

In extractingzinc from material c0n'- taining zinc in the form of oxid,the treatment of said material with sulfuric acid in the presence of anoxidizing agent including a compoundof a metal vperoxid soluble in acid.r v

5. In extracting zinc from material containing zinc in the form of oxid,the treatment of said material with sulfuric ilClCllll the presence ofan OXldlZlIlg agent including permangamc acid.

6. In extracting zinc from material con- ..taining zinc as mad, thetreatment of said material Wlill'i dilute acid containing in solution anoxidizing agent stronger in its 0x1- dizing action than is the ferricsalt of the.

said acid.

In testimony whereof I aflix my signature in the presence of twosubscribing Witnesses.

ANSON G. BETTS.

\Vitnesses ROBERT C. LIEB, BENJ. STARBUCK.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington,'D. 0.

